Abstract

The paper describes the concept of a compact, lightweight heterodyne NIR spectro-radiometer suitable for atmospheric sounding with solar occultations, and the first measurement of CO2 and CH4 absorption near 1.65 μm with spectral resolution λ/δλ~108. A highly stabilized DFB laser was used as local oscillator, while single model silica fiber Y-coupler served as a diplexer. Radiation mixed in the single mode fiber was detected by a balanced couple of InGaAs p-i-n diodes within the bandpass of ~3 MHz. Wavelength coverage of spectral measurement was provided by sweeping local oscillator frequency in the range of 1.1 cm−1. With the exposure time of 10 min, the absorption spectrum of the atmosphere over Moscow has been recorded with S/N ~120, limited by shot noise. The inversion algorithm applied to this spectrum resulted in methane vertical profile with a maximum mixing ratio of 2148 ± 10 ppbv near the surface and column density 4.59 ± 0.02·1022 cm−2.

E. Choi, K. Choi, S.-M. Yi, “Non-methane hydrocarbons in the atmosphere of a Metropolitan City and a background site in South Korea: Sources and health risk potentials,” Atmos. Environ. 45(40), 7563–7573 (2011).
[CrossRef]

E. Choi, K. Choi, S.-M. Yi, “Non-methane hydrocarbons in the atmosphere of a Metropolitan City and a background site in South Korea: Sources and health risk potentials,” Atmos. Environ. 45(40), 7563–7573 (2011).
[CrossRef]

Choi, E.

E. Choi, K. Choi, S.-M. Yi, “Non-methane hydrocarbons in the atmosphere of a Metropolitan City and a background site in South Korea: Sources and health risk potentials,” Atmos. Environ. 45(40), 7563–7573 (2011).
[CrossRef]

Choi, K.

E. Choi, K. Choi, S.-M. Yi, “Non-methane hydrocarbons in the atmosphere of a Metropolitan City and a background site in South Korea: Sources and health risk potentials,” Atmos. Environ. 45(40), 7563–7573 (2011).
[CrossRef]